The present invention relates to the optical projection upon relatively large viewing screens of the image on the face of a television receiver CRT. More specifically, the invention relates to novel apparatus for supporting and positioning a television set and associated elements for projecting the TV images for display in widescreen format.
Recently, there has been a great deal of interest in television picture display systems intended basically for home use wherein the image is presented on a viewing screen having a diagonal measurement of, say, 40 to 80 inches. Although in the earliest days of television images were projected from the face of a small, bright picture tube through an appropriate optical system to a remote screen, as typefied, for example, in U.S. Pat. Nos. 2,093,288 and 2,172,775, the early trend in the industry was toward development of picture tubes large enough to be acceptable for direct viewing rather than improvements in projection systems. However, it appears that there is now consumer demand for systems wherein the image on the face of a now standard size (e.g., 13 to 19 inch diagonal) picture tube may be projected to a much larger, remote viewing screen.
Among the various types of systems previously proposed for such purpose are those wherein the image is projected directly through a lens to a remote, rear-projection or backlight screen, such as that disclosed in U.S. Pat. No. 3,814,509; in other systems the image is reflected from mirrors and projected upon a screen mounted in the same cabinet or console with the picture tube, such as the units of U.S. Pat. Nos. 3,943,282, 3,944,734 and 4,058,837; in a third type the image is projected through a lens directly to the viewing surface of a remote, reflective screen, such as in U.S. Pat. No. 3,800,085; there are also combinations of such systems, as in U.S. Pat. No. 4,021,105. Each of the better known commercial forms of these systems require that the picture tube, which may be part of a conventional television set, be more or less permanently mounted upon or attached to the projection apparatus, or vice versa. In systems which are expressly directed to providing either projection of the CRT image on a large format screen or direct viewing thereof, typefied by aforementioned U.S. Pat. No. 3,800,085 and various commercial forms of such apparatus, an optical system including a suitable projection lens and a means defining a protected light path between the CRT face and lens is physically attached to the TV set for projection and detached therefrom for direct view. This sometimes requires physical alteration of the TV cabinet and, in any case, requires manual manipulation of screws, straps or other such retaining means each time the optical system is attached to and detached from the TV set.
It is a principal object of the present invention to provide apparatus suitable for projecting a large scale image of the picture tube face of a conventional TV set wherein the set may merely be placed upon a base support for such projection and lifted off the base for direct viewing, without physical attachment of the TV set and projection apparatus.
A further object is to provide a simple and inexpensive, yet highly reliable and durable means providing both a protected light path between the face of a TV picture tube and a projection lens, and a support for the lens allowing focusing movement thereof without physical attachment to the support.
Another object is to provide apparatus for projecting an image from the picture tube of a conventional TV set to a remote, large scale viewing screen which is easily adjustable to accommodate various size sets, to selectively change the vertical angle of the projection axis, and to effect focusing movement of the lens system.
A still further object is to provide a structure which may conveniently be formed from a single sheet of vacuum-formed plastic and serves both as an enclosed light path in an optical projection system and as a support for a lens barrel, allowing manual focusing movement of the lens system without physical attachment to the support.
In a more general sense, the object of the invention is to provide novel and improved apparatus for projecting a large scale image of a conventional TV picture which is both low in cost and superior in performance.
Other objects will in part be obvious and will in part appear hereinafter.